Genre
Periodicals
196
Congresses
12
Electronic books
7
Statistics
4
Sources
3
Tables
3
Archives
2
Bibliography
2
Classification
2
Early works to 1800
2
Biography
1
Charts, diagrams, etc
1
Databases
1
Handbooks, manuals, etc
1
Observations
1
Online resources
1
Personal narratives, American
1
Popular works
1
Textbooks
1